Hypophosphorous Acid HPA Phosphinic acid CAS 6303-21-5

Tree Chem manufactures Hypophosphorous Acid HPA CAS 6303-21-5 for customers who need high-purity or industrial-grade reducing agents in electroplating, pharmaceuticals, and specialty synthesis.

Our production technology ensures tight control of impurities such as phosphorous acid, sodium, iron, chloride, and sulfate, making the product suitable for applications requiring stable reduction behavior and minimal trace metals. For quotations or technical data, please email info@cntreechem.com.

Specification

Basic Information

Technical Specification

Applications

Water Treatment and Chemical Plating

• Hypophosphorous acid is fundamentally a strong reducing agent for aqueous systems, and its most important downstream use is in electroless (chemical) plating, especially electroless nickel. In typical electroless nickel baths, sodium hypophosphite derived from hypophosphorous acid is dosed at about 20–40 g/L together with nickel salts and complexing agents. On the catalytic metal surface, hypophosphite ions hydrolyze, releasing atomic hydrogen that reduces Ni²⁺ to metallic nickel while themselves being oxidized to higher-valent phosphorous species. This process simultaneously co-deposits phosphorus into the coating, yielding a Ni–P alloy layer with high hardness, corrosion resistance and uniform thickness even on complex geometries.
• In industrial electroless nickel lines, hypophosphite-based baths are tailored with primary complexants such as lactate or citrate and auxiliary complexants like glycine or EDTA to maintain nickel solubility and bath stability. Carefully controlled pH (around 4.5–5.0), temperature (typically 80 °C ±5 °C) and hypophosphite-to-nickel molar ratio (often 0.3–0.45) determine deposition rate, phosphorus content and coating properties. For special applications such as low-temperature plating, optimized formulations using 25–30 g/L nickel sulfate and comparable sodium hypophosphite content allow operation at 60–70 °C with appropriate stabilizers and surfactants, reducing energy consumption while maintaining coating quality.
• Hypophosphorous acid and its salts are also key components of boiler-water treatment programs as oxygen scavengers and corrosion inhibitors. When dosed into feedwater, hypophosphite reacts with dissolved oxygen, converting it into water and phosphate species, thus preventing oxygen pitting and general oxidation of steel surfaces in drums, economizers and condensate systems. It can be formulated as the main deoxygenation agent in composite boiler treatments that contain principal and auxiliary deoxygenants, dispersants and pH regulators, and it readily blends with sodium bisulfite, phosphates and organophosphonate dispersants to produce multifunctional products that deliver deoxygenation, corrosion inhibition, scale control and dispersion in one step.
• In broader water-treatment practice, hypophosphite salts participate in heavy-metal removal from industrial wastewaters. Their strong reducing power transforms higher-valent, more soluble metal species of lead, mercury, cadmium and others into less soluble forms, which precipitate and can be separated from the water stream. At the same time, hypophosphite ions may interact with calcium and magnesium to help form protective films in pipelines, improving corrosion resistance. In waste streams arising from chemical-plating operations, where phosphite and hypophosphite carry a significant phosphorus load, specialized co-precipitation agents are designed to capture these species without first oxidizing them to orthophosphate, allowing total phosphorus levels in treated effluents to be reduced to below 0.5 mg/L under optimized conditions.

Pharmaceutical and Fine Chemical Industry

• In pharmaceuticals, hypophosphorous acid serves primarily as a reactive intermediate and powerful reducing agent in multi-step syntheses. It participates in building drug intermediates by reducing specific functional groups while preserving others, allowing fine control over stereochemistry and substitution patterns. During synthesis of antibiotics, for example, hypophosphite salts are used to reduce acyl groups or intermediates associated with penicillin derivatives, ultimately helping produce sodium salts of penicillin with desired purity and stability. In antiviral-drug manufacturing, copper hypophosphite produced from the acid can be further elaborated into active antiviral intermediates.
• The compound is also a key raw material in the synthesis of vitamins, most notably vitamin B₁, where its particular phosphorous oxidation state and structural features contribute to the construction of phosphorus-containing segments in the target molecules. Because high-value pharmaceutical routes demand tight impurity control, pharmaceutical-grade hypophosphorous acid and sodium hypophosphite must meet very strict specifications, with main component content often ≥99.5 % and trace metals such as calcium, iron, lead and arsenic held at very low ppm or sub-ppm levels. This ensures that downstream reactions proceed cleanly and that finished APIs comply with pharmacopeial requirements.
• Beyond direct participation in syntheses, hypophosphorous acid can function in dosage-form development as a pH buffer and stability enhancer in certain formulations. Its ability to maintain mildly acidic conditions while providing a phosphorus source makes it suitable for specific nutrient solutions and injectable or oral preparations where controlled acidity and redox environment are important. In such applications, material selection focuses on high purity and carefully controlled anionic composition so that excipient compatibility and long-term stability are maintained.

Agriculture, Pesticides and Fertilizers

• In agriculture, hypophosphorous acid and particularly its salts (such as sodium hypophosphite and potassium hypophosphite) are widely used as pesticide raw materials, fungicides and plant nutrients. Hypophosphite-based products exhibit broad-spectrum pesticidal effects, acting against insects, fungi and mites in field crops and horticultural systems. As fungicides with systemic activity, phosphite derivatives can move within plant tissues and help control diseases such as leaf spot and rust on cereals like wheat and rice, enhancing crop health and yield.
• As intermediates in pesticide synthesis, hypophosphite salts take part in building active structures for insecticides, fungicides and herbicides. By providing phosphorus in a lower oxidation state, they contribute to the formation of P–C and P–O bonds in organophosphorus agrochemicals, increasing active ingredient load and optimizing biological performance. In many cases, phosphite-derived pesticides display higher efficacy than traditional products, with some formulations demonstrating more than 20 % improvement in pest-control efficiency while simultaneously reducing environmental impact through lower application rates or better biodegradability.
• In fertilizer applications, hypophosphorous acid and its salts serve as phosphorus sources that can be supplied via both foliar sprays and soil applications. When used in foliar nutrition, hypophosphite solutions at appropriate concentrations are sprayed directly onto leaves, providing a quickly assimilable phosphorus form that supports root growth, energy metabolism and stress tolerance. For soil treatment, hypophosphite-containing fertilizers are incorporated into the root zone, where they gradually release phosphorus and can influence soil pH, structure and moisture retention. Hypophosphite-based fertilizers and biostimulants have shown benefits in improving soil aeration, enhancing water-holding capacity and creating more favorable rhizosphere conditions, thereby strengthening plant resilience and productivity.

Metal Processing and Surface Treatment

• In metal processing, hypophosphorous acid’s central role is again linked to electroless plating, particularly for nickel and nickel–phosphorus alloy coatings. Electroless nickel processes based on sodium hypophosphite enable high-phosphorus coatings with excellent corrosion resistance, solderability and wear characteristics, widely used in automotive, machinery, electronics and petrochemical equipment. Detailed bath formulations specify nickel sulfate at roughly 25–30 g/L, sodium hypophosphite at similar levels, organic acids such as lactic acid as main complexants, and auxiliary complexants including citrate, glycine and hydroxyacetic acid, all maintained in a carefully controlled pH and temperature window to optimize deposition rate and bath stability.
• Hypophosphorous acid derivatives are also introduced into phosphate-treatment baths as functional additives to improve the quality of phosphate conversion coatings on steel and other metals. Their reducing capability helps consume hydrogen generated during phosphating, enhancing the compactness and uniformity of the phosphate layer. This leads to better corrosion protection and improved paint adhesion, which are crucial for components subjected to severe service environments. For specialty electroless plating such as low-temperature systems, hypophosphite-based baths with additional stabilizers and surfactants (including small amounts of sodium dodecyl sulfate or thiourea) provide uniform coatings at reduced operating temperatures, supporting energy-saving initiatives while maintaining coating performance.

Water Treatment, Environmental Protection and Heavy-Metal Control

• Beyond boiler systems, hypophosphorous acid and its salts are employed directly in environmental water-treatment processes. In addition to acting as reducing agents, they participate in multifactor formulations for boiler and circulating-cooling systems where deoxygenation, corrosion inhibition and scale control must all be achieved simultaneously. Products combining hypophosphite with sodium bisulfite, orthophosphates, organophosphonates and polyepoxysuccinate form a versatile toolset for controlling oxygen, dissolved metal ions and scale-forming species in complex industrial water circuits.
• In wastewaters containing heavy metals such as lead, mercury and cadmium, hypophosphite salts are used to reduce metal ions and promote their precipitation as low-solubility compounds. These precipitates are then removed by settling or filtration, reducing the concentration of toxic metals in effluent streams. In systems where phosphite-based waste is a concern—such as chemical-plating wastewater—specialized precipitation chemistries have been developed that capture hypophosphite and phosphite species through homogeneous co-precipitation, enabling compliance with ever-stricter total phosphorus discharge limits without the need for pre-oxidation to orthophosphate.

Daily Chemicals, Detergents and Personal Care

• In oral-care products, hypophosphorous acid and its sodium salts contribute to plaque and tartar control and to tooth-whitening functions. When incorporated in toothpaste, they help inhibit dental calculus formation and support removal of stains, complementing abrasive and surfactant systems to maintain oral cleanliness and freshness. Their mild acidity and reducing behavior also assist in controlling oxidative processes that could degrade flavors and sensitive actives in toothpastes and mouthwashes.
• In cosmetics and personal-care items such as lotions, creams and other skin-care formulations, hypophosphorous acid is used as a pH adjuster and skin-conditioning agent. It can gently steer the system toward the desired mildly acidic pH range while providing antioxidant and stabilizing functions, particularly in formulas containing easily oxidized oils, vitamins or botanical extracts. As a sodium hypophosphite derivative, it also acts as a stabilizer and antioxidant, slowing oxidative degradation of cosmetic ingredients and helping to maintain color, viscosity and fragrance during storage.
• Within household and industrial detergents, hypophosphite species function as builders and performance enhancers. In synthetic laundry detergents, they assist in removing oily and stubborn soils from fabrics, working alongside surfactants and other builders to deliver high cleaning efficiency. In some branded laundry powders, hypophosphite salts are included as co-builders that improve soil removal and fabric care, and in liquid detergents and cleaners they help suppress oxidation of surfactants and fragrances and protect metallic components in washing equipment and plumbing from corrosion when exposed to alkaline solutions.

Electronics, Semiconductor and Precision Cleaning

• The electronics industry makes extensive use of hypophosphorous acid and sodium hypophosphite in semiconductor manufacturing and electronic-component protection. High-purity hypophosphorous acid solutions are applied in wafer-cleaning and etching steps to remove oxide films and metallic contaminants from silicon surfaces, enabling higher device performance and yield. In specific etching formulations, hypophosphite-containing solutions are designed to control surface morphology, improving light extraction in LED chips or optimizing surface roughness in semiconductor structures.
• As part of corrosion-protection strategies for electronic components, hypophosphite-derived treatments form protective films on metals used in connectors, lead frames and circuit elements, extending service life in humid or corrosive environments. In printed-circuit-board processing, electroless nickel and nickel–gold plating systems relying on sodium hypophosphite create robust metallizations on copper circuitry, delivering excellent solderability and resistance to oxidation. Electronic-grade hypophosphorous acid and hypophosphite salts must meet stringent impurity limits to avoid introducing ionic contaminants that could compromise device reliability.

Food, Packaging and Materials Science

• In the food industry, hypophosphorous acid and its sodium salt serve as antioxidants and preservatives that extend shelf life across various products. In meat products they help inhibit oxidative rancidity and microbial spoilage, prolonging freshness and flavor. In beverages and juices they stabilize color and taste by preventing oxidation of pigments and flavor compounds, which is especially important in oxygen-sensitive formulations. Baked goods and bread benefit from improved fermentation performance and extended softness when hypophosphite-based additives are used within regulated dosage limits, typically not exceeding about 0.4 g/kg.
• In materials science, hypophosphorous acid contributes to the preparation of flame retardants and functional polymers. Its phosphorus content and reducing character are harnessed to synthesize phosphorus-containing resins and additives that raise the limiting oxygen index and improve char formation in plastics, rubbers and textiles. These flame-retardant systems are widely applied in electrical housings, construction materials and technical fabrics. As a catalyst, stabilizer or modifier, hypophosphorous acid participates in polymerization and coating processes, providing both performance benefits and processing flexibility in specialties such as functional coatings and advanced resin systems.

Analytical Chemistry and Laboratory Reagents

• In analytical chemistry, hypophosphorous acid is a versatile reagent used in reduction and deprotection reactions. It can reduce diazonium salts, effecting de-diazonation of aromatic rings, and remove halogen substituents from polynitro aromatics through reductive elimination. These reactions are valuable both in synthetic method development and in specific analytical procedures. Hypophosphorous acid is also used as a reagent for the determination of elements such as arsenic and copper, where its redox properties form the basis of titrimetric or spectrometric methods. Carefully standardized analytical grades with tightly controlled impurities are essential to ensure reproducible results in such applications.

Storage & Handling

• Store in a cool, dry, well-ventilated area.
• Keep containers tightly closed and away from heat and sunlight.
• Avoid contact with oxidizers and strong acids.
• Use corrosion-resistant equipment and ensure proper grounding.
• Handle with chemical-resistant gloves and eye protection.

Usage Notice

• Electroless nickel plating bath (standard): a solution containing 25–30 g/L nickel sulfate, 25–30 g/L sodium hypophosphite, 15–30 g/L lactic acid as the main complexant, auxiliary complexants such as 4–10 g/L sodium citrate, 4–15 g/L EDTA disodium, 5–15 g/L glycine and suitable stabilizers operates at pH 4.5–5.0 and 80 °C ±5 °C to deposit uniform Ni–P coatings on catalyzed substrates.
• Electroless nickel plating bath (general formula): a bath in which nickel salts are used at 20–30 g/L, sodium hypophosphite at 25–40 g/L, complexing agents such as 10–20 g/L sodium citrate or sodium acetate, 3–5 g/L boric acid and trace stabilizers are combined to produce high-phosphorus Ni–P coatings for corrosion-resistant applications.
• Low-temperature electroless nickel bath: a formulation containing 30 g sodium hypophosphite, 28 g nickel sulfate, 30 g sodium citrate, 25 g ammonium chloride, 10 g an organic amine, 5 mL triethanolamine, 2 g sodium dodecyl sulfate and 1 g thiourea with sodium hydroxide added to adjust pH allows electroless nickel deposition at 60–70 °C with good coating quality.
• Chemical copper electroless plating solution: an electroless copper bath where sodium hypophosphite serves as the reducing agent alongside copper salts, complexants and stabilizers provides autocatalytic copper deposition on suitably activated substrates.
• Boiler deoxygenation agent (general composition): a multi-component boiler deoxidizer consisting of 280–350 parts deoxygenation main agent based on hypophosphite chemistry, 100–160 parts auxiliary deoxygenant, 10 parts dispersant, 50–80 parts pH regulator and 460–500 parts softened water is used to remove dissolved oxygen and protect metal surfaces in feedwater systems.
• Low-phosphorus multifunctional boiler treatment: a boiler-water additive where sodium hypophosphite is blended with sodium bisulfite, phosphates and polyepoxysuccinate provides oxygen scavenging, scale inhibition, corrosion inhibition and dispersion in a single water-treatment product.
• Heavy-metal removal agent for wastewater: a hypophosphite-based treatment in which sodium hypophosphite is combined with coagulants and flocculants forms low-solubility precipitates with heavy metals such as lead, mercury and cadmium, enabling efficient removal from industrial effluents.
• Chemical plating wastewater phosphorus-removal agent: a homogeneous co-precipitation formulation designed to react directly with hypophosphite and phosphite in plating wastewater generates insoluble phosphorus-bearing precipitates that allow total phosphorus to be reduced to below about 0.5 mg/L without prior oxidation to orthophosphate.
• Pharmaceutical intermediate synthesis route: a process in which sodium hypophosphite reduces penicillin G acyl intermediates to form sodium penicillin G uses hypophosphite as the key reducing agent under controlled pH and temperature, ensuring product purity and yield.
• Vitamin B₁ synthesis step: a vitamin-production route that incorporates hypophosphorous acid as a key phosphorus-containing raw material uses its specific oxidation state and structure to build the phosphorus segment in the thiamine molecule.
• Fungicidal phosphite formulation: an agricultural fungicide in which phosphite salts derived from hypophosphorous acid are formulated at 5–15 % mass fraction with suitable solvents and adjuvants provides systemic control of leaf spot and rust diseases in cereals and other crops.
• Foliar phosphorus nutrient solution: a foliar fertilizer where sodium hypophosphite is dissolved to an appropriate concentration and sprayed on crop leaves supplies readily available phosphorus, improving growth and stress resistance while complementing basal soil fertilization.
• Soil-applied phosphite fertilizer: a fertilizer blend in which sodium hypophosphite is mixed with conventional fertilizers and incorporated into soil provides slow-release phosphorus, adjusts soil properties and enhances root development and overall plant vigor.
• Electroless nickel process control guideline: an operating practice where sodium hypophosphite is maintained at 20–40 g/L and the hypophosphite-to-nickel molar ratio at 0.3–0.45 is followed to balance deposition rate, coating phosphorus content and bath stability in Ni–P alloy plating.
• Boiler oxygen scavenger dosage regime: a dosing scheme in which hypophosphite-based agents are added to boiler feedwater at 2–5 mg/L in high-purity systems for residual oxygen removal and at higher levels in industrial boilers ensures effective deoxygenation and corrosion protection in diverse operating conditions.
• Oral-care toothpaste formula: a toothpaste containing abrasives, surfactants, humectants and a small percentage of hypophosphorous acid or its sodium salt employs the hypophosphite component to inhibit dental plaque and calculus formation while stabilizing flavors and colorants.
• Cosmetic lotion formulation: a skin-care lotion incorporating hypophosphorous acid as a pH adjuster and antioxidant together with emollients, emulsifiers and humectants uses the acid to maintain mild acidity and prevent oxidative degradation of sensitive ingredients.
• Laundry detergent additive package: a synthetic detergent in which hypophosphite salts are present at 0.1–2 % mass fraction alongside surfactants and other builders enhances removal of oily and stubborn stains while providing antioxidant and metal-protection benefits during washing.
• Semiconductor cleaning solution: a high-purity cleaning or etching solution containing 5–15 % hypophosphorous acid with carefully controlled inorganic and organic components is used to remove oxides and metal contaminants from silicon wafers while protecting surface integrity in semiconductor fabrication.
• Food antioxidant and preservative system: a food-processing formulation where hypophosphite-based additives at up to about 0.4 g/kg are incorporated into meat products, beverages or baked goods slows oxidation, extends shelf life and helps maintain desirable color and flavor profiles.

Packaging

• 25 kg plastic drum
• 250 kg plastic drum
• 1200–1250 kg IBC tank